The Microflown ® probe is a combination of a flow sensor and a sound pressure microphone. The flow sensor consists of two extremely thin, heated gold wires which are arranged in parallel. Air streaming through the sensor will cause the first wire to be cooled more than the second, which results into a difference in temperature and thus a difference  in electrical resistance which may be measured in a bridge circuit. Due to the small cross section of the wires the sensor reacts very quickly, so that a frequency range from 1 Hz to 20 kHz can be achieved. The miniature sound pressure microphone integrated into the sensor has a frequency range from 20 Hz to 20 kHz. Because of its design the sensor shows a frequency dependant sensitivity which is taken into account in the software in respect to amplitude and phase as well...

Alternativ kann das System auch mit einer klassischen Schallintensitätssonde, bestehend aus zwei phasenangepasten Schalldruckmikrofonen mit einem definierten Abstand, betrieben werden. Bei diesem Sondentyp wird die Schallschnelle aus dem Phasenunterschied der beiden Schalldrucksignale berechnet.